A frame structure of a press apparatus (a press machine) is generally classified as a C type or a portal type from a shape thereof. A press apparatus having a C-shaped frame structure is widely used because workability from a front surface is good in comparison with a press apparatus having a portal frame structure.
FIG. 4 shows an example of a conventional structure of a press apparatus having such a C-shaped frame structure.
A press apparatus 1 shown in FIG. 4 includes a C-shaped frame 2, a fixed die 3 and a movable die 4.
The C-shaped frame 2 is configured by combining a lower frame 5, an intermediate frame 6 and an upper frame 7 in a C shape in which a front side in a forward and rearward direction and both sides in a leftward and rightward direction are open.
Further, among “a forward and rearward direction,” “a leftward and rightward direction” and “an upward and downward direction,” which are perpendicular to each other in the press apparatus, “the forward and rearward direction” is a leftward and rightward direction in the drawings, “the leftward and rightward direction” is a direction perpendicular to surfaces of the drawings, i.e., a front and back sides of the drawings, and “the upward and downward direction” is an upward and downward direction in the drawings. In addition, “a front side” of “the forward and rearward direction” is a right side in the drawings, and “a rear side” of “the forward and rearward direction” is a left side in the drawings.
The fixed die 3 is supported by and fixed to an upper surface of the lower frame 5.
The movable die 4 is supported movably with respect to the upper frame 7 in the upward and downward direction while being disposed above the fixed die 3. For this reason, specifically, the movable die 4 is supported movably in the upward and downward direction by a hydraulic or electrically-operated cylinder (not shown) assembled on the upper frame 7.
When pressing of a workpiece is performed using the press apparatus 1 having the above-mentioned configuration, for example, in a state in which the movable die 4 is retracted upward from the fixed die 3 and the workpiece is set on the fixed die 3 or the movable die 4, the movable die 4 is moved downward toward the fixed die 3. Accordingly, predetermined pressing such as shearing, bending, drawing, forging, or the like, is performed on the workpiece between the fixed die 3 and the movable die 4.